Laws of Logic

Use the law of syllogism to draw a conclusion from the two given statements:
Statement 1: If you exercise regularly, then you have a healthy body
Statement 2: If you have a healthy body, then you have more energy

• You have more energy
• If you exercise regularly, then you have more energy
• You have a healthy body
• If you do not have a healthy body, then you do not exercise regularly

Use the Law of Detachment to draw a conclusion from the two given statements. If not possible, write not possible.
Statement 1: If I study for one hour each day, then I will score well on the exam
Statement 2: I will score well on the exam

•  I study for 1 hour each day.
• I do not study for 1 hour each day
• If I do well on the exam, I studied for 1 hour each day.
• not possible

If possible, use the Law of Detachment to draw a conclusion from the two given statements. If not possible, write not possible.
Statement 1: If x = 2, then 2x – 10 = –6.
Statement 2: x = 2 

• 2x – 10 = –6 
• x = 2
•  If 2x – 10 = –6, then x = 2
• not possible 

Which law of deductive reasoning is being used, if any?
If a triangle is equilateral, then all three sides are congruent. 
If all the sides of a triangle are congruent, then the angles opposite them are congruent. 
Therefore, if a triangle is equilateral, then the angles opposite the sides are congruent.

• Law of Detachment
• Law of Syllogism
• Law of the Contrapositive
• Not valid

What is a valid counterexample for the following statement? "If an animal is a panther, then it lives in the forest."

• It lives in a zoo.
• No counterexample, this is true.
• It lives in an aquarium.
• It is a monkey

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CCSS.HSS.CP.A.5

Using the Law of Syllogism, which of the following completes the statement to form a valid conclusion?
If it is snowing heavily, then school will be canceled.
If school is canceled, the big test will not be given today.
It is snowing heavily, therefore

• look out for the snowplows while driving to school.
• the big test will not be given today.
• the roads will be hard to drive on.
• you should call the school to see if school is canceled.

Which law of deductive reasoning is being used, if any?
If a triangle is equilateral, then all three sides are congruent. 
If all the sides of a triangle are congruent, then the angles opposite them are congruent. 
Therefore, if a triangle is equilateral, then the angles opposite the sides are congruent.

• Law of Detachment
• Law of Syllogism
• Law of the Contrapositive
• Not valid

Which law of logic is this:
If I buy a dress, then I won't get chips.
I bought a dress.
Therefore, I won't get chips.

• Law of Detachment
• Law of Contrapositive
• Law of Syllogism
• Law of Biconditional

p→q
q→r
∴p→r
Which law is modeled?

• Law of Syllogism
• Law of Detachment
• Law of Contrapositive
• Law of Shannon

p→q
p
∴q
Which law is modeled?

• Law of Syllogism
• Law of Detachment
• Law of Contrapositive
• Law of Shannon